Endovascular neurologic interventions are increasing in frequency and complexity. Devices are being placed above the Circle of Willis. Currently, interventionalists are judging accessibility via the proximal vessels using only subjective estimations from 2D angiograms. As a result, complication rates during procedures are as high as 10%. Calculation of the tortuosity of vessels can be performed from data extracted from computed tomography angiography (CTA), magnetic resonance angiography (MRA), and biplane or rotational angiograms, but the intervention a list also needs feedback of catheter position relative to the vasculature during the procedure. In addition, models are needed to estimate patient risk prior to placement. The goal of the proposed research is safer neuro-endovascular procedures, achieved by developing a system that can provide the interventionalist with information on vessel tortuosity, accessibility, device position, and potential complications during the procedure prior to and during device placement. Therefore, we propose to determine the hitherto unavailable quantities of curvature of, tortuosity of, and accessibility via the carotid, vertebral, and basilar arteries. Moreover, we will develop innovative, new techniques for estimating position and orientation of catheters, angioplasty balloons, and stents relative to vessel walls (proximity) and fusing this information with the vascular information for use during the procedure. With this information, we will develop models relating curvature, tortuosity, and proximity to complications so that the interventionalist can make more informed decisions regarding patient treatment involving interventional devices prior to and during attempts at placement, and thereby, reduce patient mortality and morbidity. With curvature and tortuosity available during interventional neurovascular procedures, coupled with relative 3D catheter positions and calculated probabilities of complications, we expect to improve access decisions as well as interventional device decisions. The impact of the proposed research is expected to lead to a substantial reduction of mortality and morbidity associated with neurovascular procedures.